Add support for AES-128-CMAC and AES-CMAC-PRF-128
diff --git a/library/cmac.c b/library/cmac.c
new file mode 100644
index 0000000..73ee6d0
--- /dev/null
+++ b/library/cmac.c
@@ -0,0 +1,527 @@
+/*
+ * NIST SP800-38B compliant CMAC implementation
+ *
+ * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * This file is part of mbed TLS (https://tls.mbed.org)
+ */
+
+/*
+ * Definition of CMAC:
+ * http://csrc.nist.gov/publications/nistpubs/800-38B/SP_800-38B.pdf
+ * RFC 4493 "The AES-CMAC Algorithm"
+ */
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "mbedtls/config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#if defined(MBEDTLS_CMAC_C)
+
+#include "mbedtls/cmac.h"
+
+#include <string.h>
+
+#if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C)
+#if defined(MBEDTLS_PLATFORM_C)
+#include "mbedtls/platform.h"
+#else
+#include <stdio.h>
+#define mbedtls_printf printf
+#endif /* MBEDTLS_PLATFORM_C */
+#endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */
+
+/*
+ * Macros for common operations.
+ * Results in smaller compiled code than static inline functions.
+ */
+
+/*
+ * XOR 128-bit
+ */
+#define XOR_128(i1, i2, o) \
+ for( i = 0; i < 16; i++ ) \
+ ( o )[i] = ( i1 )[i] ^ ( i2 )[i];
+
+/*
+ * Update the CMAC state in Mn using an input block x
+ * TODO: Compiler optimisation
+ */
+#define UPDATE_CMAC( x ) \
+ XOR_128( Mn, ( x ), Mn ); \
+ if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, Mn, 16, Mn, &olen ) ) != 0 ) \
+ return( ret );
+
+/* Implementation that should never be optimized out by the compiler */
+static void mbedtls_zeroize( void *v, size_t n ) {
+ volatile unsigned char *p = v; while( n-- ) *p++ = 0;
+}
+
+/*
+ * Initialize context
+ */
+void mbedtls_cmac_init( mbedtls_cmac_context *ctx )
+{
+ memset( ctx, 0, sizeof( mbedtls_cmac_context ) );
+}
+
+/*
+ * Leftshift a 16-byte block by 1 bit
+ * \note output can be same as input
+ */
+static void leftshift_onebit(unsigned char *input, unsigned char *output)
+{
+ int i;
+ unsigned char temp;
+ unsigned char overflow = 0;
+
+ for( i = 15; i >= 0; i-- )
+ {
+ temp = input[i];
+ output[i] = temp << 1;
+ output[i] |= overflow;
+ overflow = temp >> 7;
+ }
+ return;
+}
+
+/*
+ * Generate subkeys
+ */
+static int generate_subkeys(mbedtls_cmac_context *ctx)
+{
+ static const unsigned char Rb[2] = {0x00, 0x87}; /* Note - block size 16 only */
+ int ret;
+ unsigned char L[16];
+ size_t olen;
+
+ /* Calculate Ek(0) */
+ memset( L, 0, 16 );
+ if( ( ret = mbedtls_cipher_update( &ctx->cipher_ctx, L, 16, L, &olen ) ) != 0 )
+ {
+ return( ret );
+ }
+
+ /*
+ * Generate K1
+ * If MSB(L) = 0, then K1 = (L << 1)
+ * If MSB(L) = 1, then K1 = (L << 1) ^ Rb
+ */
+ leftshift_onebit( L, ctx->K1 );
+ ctx->K1[15] ^= Rb[L[0] >> 7]; /* "Constant-time" operation */
+
+ /*
+ * Generate K2
+ * If MSB(K1) == 0, then K2 = (K1 << 1)
+ * If MSB(K1) == 1, then K2 = (K1 << 1) ^ Rb
+ */
+ leftshift_onebit( ctx->K1, ctx->K2 );
+ ctx->K2[15] ^= Rb[ctx->K1[0] >> 7]; /* "Constant-time" operation */
+
+ return( 0 );
+}
+
+int mbedtls_cmac_setkey( mbedtls_cmac_context *ctx,
+ mbedtls_cipher_id_t cipher,
+ const unsigned char *key,
+ unsigned int keybits )
+{
+ int ret;
+ const mbedtls_cipher_info_t *cipher_info;
+
+ cipher_info = mbedtls_cipher_info_from_values( cipher, keybits, MBEDTLS_MODE_ECB );
+ if( cipher_info == NULL )
+ return( MBEDTLS_ERR_CMAC_BAD_INPUT );
+
+ if( cipher_info->block_size != 16 )
+ return( MBEDTLS_ERR_CMAC_BAD_INPUT );
+
+ mbedtls_cipher_free( &ctx->cipher_ctx );
+
+ if( ( ret = mbedtls_cipher_setup( &ctx->cipher_ctx, cipher_info ) ) != 0 )
+ return( ret );
+
+ if( ( ret = mbedtls_cipher_setkey( &ctx->cipher_ctx, key, keybits,
+ MBEDTLS_ENCRYPT ) ) != 0 )
+ {
+ return( ret );
+ }
+
+ return( generate_subkeys(ctx) );
+}
+
+/*
+ * Free context
+ */
+void mbedtls_cmac_free( mbedtls_cmac_context *ctx )
+{
+ mbedtls_cipher_free( &ctx->cipher_ctx );
+ mbedtls_zeroize( ctx, sizeof( mbedtls_cmac_context ) );
+}
+
+/* TODO: Use cipher padding function? */
+static void padding(const unsigned char *lastb, unsigned char *pad, const size_t length)
+{
+ size_t j;
+
+ /* original last block */
+ for( j = 0; j < 16; j++ )
+ {
+ if( j < length )
+ {
+ pad[j] = lastb[j];
+ }
+ else if( j == length )
+ {
+ pad[j] = 0x80;
+ }
+ else
+ {
+ pad[j] = 0x00;
+ }
+ }
+}
+
+/*
+ * Generate tag on complete message
+ */
+static int cmac_generate( mbedtls_cmac_context *ctx, size_t length,
+ const unsigned char *input,
+ unsigned char *tag, size_t tag_len )
+{
+ unsigned char Mn[16];
+ unsigned char M_last[16];
+ unsigned char padded[16];
+ int n, i, j, ret, flag;
+ size_t olen;
+
+ /*
+ * Check length requirements: SP800-38B A
+ * 4 is a worst case bottom limit
+ */
+ if( tag_len < 4 || tag_len > 16 || tag_len % 2 != 0 )
+ return( MBEDTLS_ERR_CMAC_BAD_INPUT );
+
+ /* TODO: Use cipher padding function? */
+ // mbedtls_cipher_set_padding_mode( ctx->cipher, MBEDTLS_PADDING_ONE_AND_ZEROS );
+
+ n = ( length + 15 ) / 16; /* n is number of rounds */
+
+ if( n == 0 )
+ {
+ n = 1;
+ flag = 0;
+ }
+ else
+ {
+ flag = ( ( length % 16 ) == 0);
+ }
+
+ /* Calculate last block */
+ if( flag )
+ {
+ /* Last block is complete block */
+ XOR_128( &input[16 * (n - 1)], ctx->K1, M_last );
+ }
+ else
+ {
+ /* TODO: Use cipher padding function? */
+ padding( &input[16 * (n - 1)], padded, length % 16 );
+ XOR_128( padded, ctx->K2, M_last );
+ }
+
+ memset( Mn, 0, 16 );
+
+ for( j = 0; j < n - 1; j++ )
+ {
+ UPDATE_CMAC(&input[16 * j]);
+ }
+
+ UPDATE_CMAC(M_last);
+
+ memcpy( tag, Mn, 16 );
+
+ return( 0 );
+}
+
+int mbedtls_cmac_generate( mbedtls_cmac_context *ctx, size_t length,
+ const unsigned char *input,
+ unsigned char *tag, size_t tag_len )
+{
+ return( cmac_generate( ctx, length, input, tag, tag_len ) );
+}
+
+/*
+ * Authenticated decryption
+ */
+int mbedtls_cmac_verify( mbedtls_cmac_context *ctx, size_t length,
+ const unsigned char *input,
+ const unsigned char *tag, size_t tag_len )
+{
+ int ret;
+ unsigned char check_tag[16];
+ unsigned char i;
+ int diff;
+
+ if( ( ret = cmac_generate( ctx, length, input, check_tag, tag_len) ) != 0 )
+ {
+ return ret;
+ }
+
+ /* Check tag in "constant-time" */
+ for( diff = 0, i = 0; i < tag_len; i++ )
+ {
+ diff |= tag[i] ^ check_tag[i];
+ }
+
+ if( diff != 0 )
+ {
+ return( MBEDTLS_ERR_CMAC_VERIFY_FAILED );
+ }
+
+ return( 0 );
+}
+
+int mbedtls_aes_cmac_prf_128( mbedtls_cmac_context *ctx, size_t length,
+ const unsigned char *key, size_t key_length,
+ const unsigned char *input,
+ unsigned char *tag )
+{
+ int ret;
+ unsigned char zero_key[16];
+ unsigned char int_key[16];
+
+ if( key_length == 16 )
+ {
+ /* Use key as is */
+ memcpy(int_key, key, 16);
+ }
+ else
+ {
+ mbedtls_cmac_context zero_ctx;
+
+ /* Key is AES_CMAC(0, key) */
+ mbedtls_cmac_init( &zero_ctx );
+ memset(zero_key, 0, 16);
+ ret = mbedtls_cmac_setkey( &zero_ctx, MBEDTLS_CIPHER_ID_AES, zero_key, 8 * sizeof zero_key );
+ if( ret != 0 )
+ {
+ return( ret );
+ }
+ ret = mbedtls_cmac_generate( &zero_ctx, key_length, key, int_key, 16 );
+ if( ret != 0 )
+ {
+ return( ret );
+ }
+ }
+
+ ret = mbedtls_cmac_setkey( ctx, MBEDTLS_CIPHER_ID_AES, int_key, 8 * sizeof int_key );
+ if( ret != 0 )
+ {
+ return( ret );
+ }
+ return( mbedtls_cmac_generate( ctx, length, input, tag, 16 ) );
+}
+
+#if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C)
+/*
+ * Examples 1 to 4 from SP800-3B corrected Appendix D.1
+ * http://csrc.nist.gov/publications/nistpubs/800-38B/Updated_CMAC_Examples.pdf
+ */
+
+#define NB_CMAC_TESTS 4
+#define NB_PRF_TESTS 3
+
+/* Key */
+static const unsigned char key[] = {
+ 0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6,
+ 0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c
+};
+
+/* Assume we don't need to test Ek0 as this is a function of the cipher */
+
+/* Subkey K1 */
+static const unsigned char K1[] = {
+ 0xfb, 0xee, 0xd6, 0x18, 0x35, 0x71, 0x33, 0x66,
+ 0x7c, 0x85, 0xe0, 0x8f, 0x72, 0x36, 0xa8, 0xde
+};
+
+/* Subkey K2 */
+static const unsigned char K2[] = {
+ 0xf7, 0xdd, 0xac, 0x30, 0x6a, 0xe2, 0x66, 0xcc,
+ 0xf9, 0x0b, 0xc1, 0x1e, 0xe4, 0x6d, 0x51, 0x3b
+};
+
+/* All Messages */
+static const unsigned char M[] = {
+ 0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96,
+ 0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
+ 0xae, 0x2d, 0x8a, 0x57, 0x1e, 0x03, 0xac, 0x9c,
+ 0x9e, 0xb7, 0x6f, 0xac, 0x45, 0xaf, 0x8e, 0x51,
+ 0x30, 0xc8, 0x1c, 0x46, 0xa3, 0x5c, 0xe4, 0x11,
+ 0xe5, 0xfb, 0xc1, 0x19, 0x1a, 0x0a, 0x52, 0xef,
+ 0xf6, 0x9f, 0x24, 0x45, 0xdf, 0x4f, 0x9b, 0x17,
+ 0xad, 0x2b, 0x41, 0x7b, 0xe6, 0x6c, 0x37, 0x10
+};
+
+static const unsigned char T[NB_CMAC_TESTS][16] = {
+ {
+ 0xbb, 0x1d, 0x69, 0x29, 0xe9, 0x59, 0x37, 0x28,
+ 0x7f, 0xa3, 0x7d, 0x12, 0x9b, 0x75, 0x67, 0x46
+ },
+ {
+ 0x07, 0x0a, 0x16, 0xb4, 0x6b, 0x4d, 0x41, 0x44,
+ 0xf7, 0x9b, 0xdd, 0x9d, 0xd0, 0x4a, 0x28, 0x7c
+ },
+ {
+ 0xdf, 0xa6, 0x67, 0x47, 0xde, 0x9a, 0xe6, 0x30,
+ 0x30, 0xca, 0x32, 0x61, 0x14, 0x97, 0xc8, 0x27
+ },
+ {
+ 0x51, 0xf0, 0xbe, 0xbf, 0x7e, 0x3b, 0x9d, 0x92,
+ 0xfc, 0x49, 0x74, 0x17, 0x79, 0x36, 0x3c, 0xfe
+ }
+};
+
+/* Sizes in bytes */
+static const size_t Mlen[NB_CMAC_TESTS] = {
+ 0,
+ 16,
+ 40,
+ 64
+};
+
+/* PRF K */
+static const unsigned char PRFK[] = {
+ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+ 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+ 0xed, 0xcb
+};
+
+/* Sizes in bytes */
+static const size_t PRFKlen[NB_PRF_TESTS] = {
+ 18,
+ 16,
+ 10
+};
+
+/* PRF M */
+static const unsigned char PRFM[] = {
+ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+ 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+ 0x10, 0x11, 0x12, 0x13
+};
+
+static const unsigned char PRFT[NB_PRF_TESTS][16] = {
+ {
+ 0x84, 0xa3, 0x48, 0xa4, 0xa4, 0x5d, 0x23, 0x5b,
+ 0xab, 0xff, 0xfc, 0x0d, 0x2b, 0x4d, 0xa0, 0x9a
+ },
+ {
+ 0x98, 0x0a, 0xe8, 0x7b, 0x5f, 0x4c, 0x9c, 0x52,
+ 0x14, 0xf5, 0xb6, 0xa8, 0x45, 0x5e, 0x4c, 0x2d
+ },
+ {
+ 0x29, 0x0d, 0x9e, 0x11, 0x2e, 0xdb, 0x09, 0xee,
+ 0x14, 0x1f, 0xcf, 0x64, 0xc0, 0xb7, 0x2f, 0x3d
+ }
+};
+
+
+int mbedtls_cmac_self_test( int verbose )
+{
+ mbedtls_cmac_context ctx;
+ unsigned char tag[16];
+ int i;
+ int ret;
+
+ mbedtls_cmac_init( &ctx );
+
+ if( mbedtls_cmac_setkey( &ctx, MBEDTLS_CIPHER_ID_AES, key, 8 * sizeof key ) != 0 )
+ {
+ if( verbose != 0 )
+ mbedtls_printf( " CMAC: setup failed" );
+
+ return( 1 );
+ }
+
+ if( ( memcmp( ctx.K1, K1, 16 ) != 0 ) ||
+ ( memcmp( ctx.K2, K2, 16 ) != 0 ) )
+ {
+ if( verbose != 0 )
+ mbedtls_printf( " CMAC: subkey generation failed" );
+
+ return( 1 );
+ }
+
+ for( i = 0; i < NB_CMAC_TESTS; i++ )
+ {
+ mbedtls_printf( " AES-128-CMAC #%u: ", i );
+
+ ret = mbedtls_cmac_generate( &ctx, Mlen[i], M, tag, 16 );
+ if( ret != 0 ||
+ memcmp( tag, T[i], 16 ) != 0 )
+ {
+ if( verbose != 0 )
+ mbedtls_printf( "failed\n" );
+
+ return( 1 );
+ }
+ ret = mbedtls_cmac_verify( &ctx, Mlen[i], M, T[i], 16 );
+ if( ret != 0 )
+ {
+ if( verbose != 0 )
+ mbedtls_printf( "failed\n" );
+
+ return( 1 );
+ }
+
+ if( verbose != 0 )
+ mbedtls_printf( "passed\n" );
+ }
+
+ for( i = 0; i < NB_PRF_TESTS; i++ )
+ {
+ mbedtls_printf( " AES-CMAC-128-PRF #%u: ", i );
+
+ mbedtls_aes_cmac_prf_128( &ctx, 20, PRFK, PRFKlen[i], PRFM, tag);
+
+ if( ret != 0 ||
+ memcmp( tag, PRFT[i], 16 ) != 0 )
+ {
+ if( verbose != 0 )
+ mbedtls_printf( "failed\n" );
+
+ return( 1 );
+ }
+
+ if( verbose != 0 )
+ mbedtls_printf( "passed\n" );
+ }
+
+ mbedtls_cmac_free( &ctx );
+
+ if( verbose != 0 )
+ mbedtls_printf( "\n" );
+
+ return( 0 );
+}
+
+#endif /* MBEDTLS_SELF_TEST && MBEDTLS_AES_C */
+
+#endif /* MBEDTLS_CMAC_C */